I've been keeping up with the nightly builds of Firefox, and I honestly don't believe that it's ready for a new version number yet. However, it's definitely been released and is available here: Firefox 0.9 RC.

This new version features various improvements over 0.8, but it is still pretty far from complete in terms of bugs and features they had planned to implement. But I think the biggest problem is the new theme. Many Firefox users have complained about the new theme (Another default theme coming), which was decided to replace the Qute theme that was previously the default in Firefox for both legal reasons (which I believe have since been cleared up anyway) and in order to maintain a more uniform look cross-platform. The guys who made the new theme have said that it isn't nearly finished, and that it will probably look much better by the time it is done. However, I feel that that's more of a reason not to ship a release candidate yet.

For those of you who liked the old theme, you can download it for Firefox 0.9 here: Qute theme for Firefox 0.9. I switched as soon as I saw it was available.